The U.S. Supreme Court ruled Tuesday that an Indian tribe cannot be prosecuted by the state of Michigan for opening what local authorities deemed to be an illegal casino.

The top U.S. court affirmed the “sovereign immunity” of the Bay Mills tribe in the 5-4 decision, with the majority maintaining it was up to the Congress, and not the courts, to decide the limits of that immunity.

“Congress has not abrogated tribal sovereign immunity from a state’s suit to enjoin gaming off a reservation or other Indian lands.

“Indian tribes have immunity even when a suit arises from off-reservation commercial activity,” it said.

The case before the nine justices involved a suit brought by the state of Michigan against the Bay Mills tribe which installed a casino in the town of Vanderbilt, about 12 miles (20 kilometers) from its reservation.

The tribe initially built a small casino with 38 slot machines, and then expanded it to 84 slot machines.

Michigan argued that the land on which the casino was built was not Indian lands — something the tribe disputed– and that therefore it was operating a casino in violation of federal law.

A 1998 law authorizes native American tribes under certain conditions to run slot machines and other gambling operations in their reservations, even when it is illegal on the national level.

During the arguments over the case, the lawyer for the state of Michigan, John Bursch, asked why a native American tribe would have immunity in operating an illegal casino, when a sovereign country like France would have to respond to the courts.